1. Field of the Invention
The invention relates to optical touch control systems, and more particularly to optical touch control systems with reduced manufacturing costs and enhanced accuracy in touch control.
2. Description of the Related Art
In an optical touch control system, touch control operations are identified by image sensors detecting interception of optical paths.
Referring to FIG. 1, a conventional optical touch control system 1 comprises a monitor 10, a support frame 11, three retro-reflective layers 12, two light sources 13, and two image sensors 14.
The support frame 11 surrounds three sides of the monitor 10 and is an annular construction with an opening.
The retro-reflective layers 12 are attached to inner sides of the support frame 11, respectively.
The light sources 13 are disposed at the opening of the support frame 11 and oppose each other.
The image sensors 14 are also disposed at the opening of the support frame 11 and oppose each other. Here, the image sensors 14 are adjacent to the light sources 13, respectively.
During operation of the optical touch control system 1, incident light output from the light sources 13 are reflected back by the retro-reflective layers 12 along an incident route of the incident light and are received by the image sensors 14. Here, by the image sensors 14 detecting interception of an optical path in any position on the monitor 10, identification of touch control can be obtained.
Nevertheless, because of inherently restricted properties possessed by the retro-reflective layers 12, when the incident angle of the incident light output from the light sources 13 increase, the intensity or energy of the light reflected back along the incident route reduces, such that uniformity of brightness distribution of the light received by the image sensors 14 is poor. Moreover, the retro-reflective layers 12 are unstable in manufacturing. Specifically, the uniformity of the brightness distribution of the light received by the image sensors 14 is affected by micro-structure of the retro-reflective layers 12, a high-frequency sealing treatment applied to the retro-reflective layers 12, uniformity of cladding layers of the retro-reflective layers 12, and flatness of the retro-reflective layers 12 attached to the support frame 11. Accordingly, even though the optical touch control system 1 employs the retro-reflective layers 12 of the same batch, the uniformity of the brightness distribution of the light may often be inconsistent, thereby causing programming calculation errors, and further resulting in abnormal touch control operations.
Referring to FIG. 2, another conventional optical touch control system 2 comprises a monitor 20, three light guides 21, a plurality of light sources 22, and two image sensors 23.
The light guides 21 surround three sides of the monitor 20, forming an opening.
The light sources 22 are respectively disposed on outer sides of the light guides 21 and output light toward the light guides 21 and the top of monitor 20.
The image sensors 23 are respectively disposed at the opening of the light guides 21 and oppose each other.
During operation of the optical touch control system 2, incident light output from the light sources 22 goes to the top of the monitor 20 through the light guides 21 and is received by the image sensors 23. Here, by the image sensors 23 detecting interception of an optical path in any position on the monitor 20, identification of touch control can be obtained.
Nevertheless, as the multiple light sources 22 must be respectively disposed on the outer sides of the light guides 21, manufacturing costs of the optical touch control system 2 are high. Here, even though the number of the light sources 22 is designed to be minimal, i.e. only one light source 22 is disposed on the outer side of each light guide 21, at least three light sources 22 are required by the optical touch control system 2. Moreover, as the multiple light sources 22 are respectively disposed on the outer sides of the light guides 21, the overall size of the optical touch control system 2 cannot be reduced, adversely affecting application of the optical touch control system 2 to a small-size electronic device.